DESCRIPTION: The investigators propose to test the feasibility of developing a array of avalanche photodiodes for potential use in an optical detection system for oxygen saturation or blood flow, as further described by their abstract: "Optical detection and imaging has the potential for monitoring diagnostically important parameters including hemoglobin concentration, oxygen saturation, an blood flow, as well as dosimetry for photo-dynamic therapy, imaging tumors, an organs in the human body. The emergence of optical-source diagnostic technique relies on accurately quantifying very low levels of severely scattered and attenuated light as well as their temporal characteristics. "Optical sensors used in medical optical diagnostic systems such as blood oxymeters and blood Doppler flowmeters limit the usefulness of these systems. At this time no multi-element, solid-state detector exists which has the fast time response, sensitivity to low light levels, compact design, and low fabrication cost required to produce advances in widely disseminated, portable optical diagnostic instrumentation. "In the Phase I-Phase II program we propose to design and test a novel, integrated solid-state system that integrates new optical monitoring diagnostic concepts and improves upon pulse-oxymetry and laser Doppler blood flowmetry. This effort will be collaboration between Radiation Monitoring Devices, Inc. and Professor David Boas of the Electro-Optics Technology Center, Tufts University. The new system will be based on an array of solid-state, micro-avalanche photodiode (micrometer APD) detectors developed recently by RMD, Inc. These sensors combine high internal gain and small photosite areas ranging from less than 100 micrometers m2 to greater than 10 4 micrometers m2 using standard silicon integrated circuit planar technology. These sensors have single-photon sensitivity and high internal gain, small size, low operating voltage, noise and power requirements." PROPOSED COMMERCIAL APPLICATION: Not available.